Pearls hold many fascinating secrets, from Cleopatra famously dissolving one in wine to prove her wealth, to Cartier trading a Fifth Avenue mansion for a single pearl necklace. Their history is as rich as their lustre. But what truly sets pearls apart is their origin: unlike any other gemstone, they are the only ones created by living creatures. Formed within molluscs, these organic gems are rare treasures of the natural world.
At Thomas Glover, we are celebrating the birthstone of June and exploring 10 things you may not know about pearls.
Pearls are the world's oldest gemstone
As the renowned 19th-century gemologist George Kunz observed, it was likely the ancient fish-eating tribes who first recognised the beauty of pearls. Drawn to their soft iridescence as they opened oysters for sustenance, these early coastal communities appreciated pearls long before pearls graced royal courts or sacred regalia.
Pearls are considered the oldest known gemstones, with origins tracing back millions of years. The earliest known example of pearl jewellery dates back to circa 350 BC, discovered by archaeologists within the sarcophagus of a Persian princess, in the ancient city of Susa, known as the 'Susa necklace'. The necklace consisted of 216 pearls strung in three rows and bound with bronze wire, divided by ten gold bars, each formed of three small disks. Today, this ancient treasure is in the Louvre’s Persian collection.
Victorian Pearl & Diamond Drop Earrings c.1890
Pearls take years to form
Pearls begin when a tiny irritant such as a grain of sand enters a mollusc’s shell. In response, the mollusc secretes nacre, a smooth, iridescent substance also known as mother-of-pearl, to coat the irritant, gradually building up to form the pearl.
Depending on the type and environment, a pearl may take anywhere from several months to up to eight years to fully form.
Cultured and 'freshwater' pearls develop more quickly, while rarer saltwater varieties can take nearly a decade.
Every pearl is unique
Each pearl is a one-of-a-kind creation. Whether formed naturally or cultured, no two are exactly alike. Their subtle differences in shape, surface, and lustre are not imperfections, but rather the marks of authenticity. Cultured pearls are created by a small bead being inserted into the mollusc, a technique developed in 1893 by Kokichi Mikimoto in Japan who realised he could produce these sought after gems in a faster and more economical way, this brought pearls to a wider market and was a technique which rapidly caught on.
Victorian Diamond and Pearl Necklace c.1890
4. They are one of the most varied gemstones in the world
While each pearl is unique, they can be categorised in various ways. Pearls are classified as either natural or cultured, and as freshwater or saltwater. Within cultured saltwater pearls, there are three main types - Akoya, known for their classic round shape; Tahitian, known for their dark overtones; and South Sea, known for their large size and golden lustre.
Each type has its own unique appeal, shaped by the species of mollusc, the waters they inhabit, and the time it takes to form. Though there are more than 50,000 mollusc species worldwide, only a select few are capable of producing pearls suitable for fine jewellery, making each pearl a rare and beautiful gift from nature.
Georgian Seed Pearl Suite circa 1790
5. Natural pearls are extremely rare
Unlike cultured pearls, cultivated under controlled conditions, natural pearls occur purely by chance. A wild oyster may produce a pearl once in its lifetime, and even then, the odds of finding one of true gem quality are incredibly slim and it is estimated only 1 in 1000 oysters produces a pearl and of these not every one is gem quality.
What makes them even more elusive today is the environmental impact of overharvesting and habitat loss, which has dramatically reduced wild pearl oyster populations. It is believed that 90% of natural saltwater pearls on the market were harvested over 90 years ago. This increasing rarity has led to a significant rise in the value of natural pearls over recent decades.
A selection of conch pearls
Not all pearls can be cultivated
Among the most distinctive and elusive of pearls are conch pearls, which are not only rare in colour and their unique formation. Found within the Queen Conch mollusc in Caribbean waters, these pearls often appear oval or elongated, with a pink to orange colour, smooth surface and natural flame-like pattern. Unlike traditional pearls, conch pearls contain no nacre, which gives them their singular satin-like glow rather than the typical iridescence. Because they cannot be cultured and are found only by chance, each conch pearl is an extraordinary rarity.
Pearls have their own grading system
Pearls are graded using their own unique system, focusing on six key qualities: lustre, surface quality, shape, colour, size, and nacre depth. Pearls are typically graded on a scale from A to AAA, with AAA representing the highest quality.
At Thomas Glover, we hand-select each pearl based on these standards, ensuring every piece in our collection reflects the finest in natural beauty.
A selection of Victorian pearl star brooches
Pearls can vary in value by millions
The value of a pearl can range dramatically, from modestly priced cultured varieties to natural pearls worth millions. Several factors contribute to this wide spectrum, including origin, rarity, size, shape, surface quality, and lustre.
Natural pearls are the rarest and most valuable, especially those from historic sources like the Persian Gulf. Historically, the Persian Gulf was the epicentre of the natural pearl world. Up until the mid-20th century, around 75% of all natural pearls originated from its bountiful oyster beds, especially off Bahrain and along the Gulf of Mannar.
Antique Pearl and Diamond Daisy Cluster Ring c.1910
9. Pearls are rich in symbolism
Their rich history and widespread popularity mean that they have been used to represent many different things across the world, including wisdom, fertility, perfection, purity and innocence.
In the modern Western world, pearls represent the 30th wedding anniversary and are one of June’s birthstones, alongside alexandrite and moonstone.
10. Pearls must be carefully looked after
With proper care, pearls can last for generations. Yet, they are among the softest gemstones and must be worn with caution to avoid damage.
Avoid exposure to harsh chemicals, store them safely in a soft cloth, and consider occasional professional cleaning to preserve their radiant lustre. Necklaces of pearls which have been strung onto silk will need professionally restringing every couple of years to protect the pearls - this is something we can help you with when needed.
